- There are a number of transdermal drug delivery systems that exist in the United States.
- The majority of Fentanyl patches made available are reservoir membrane-modulated systems.
A recent case that was reported to the Institute for Safe Medication Practices made headlines as a physician instructed one of his staff to cut one 50 mcg/h transdermal system patch of Fentanyl in half to apply on a patient delivered in a 25mcg/h dose. Soon after, the patient’s visiting nurse discovered the patch and removed it immediately. The nurse then called the physician to notify him about the risks of Fentanyl overdose with such practice.
While the patient was fortunately saved from adverse effects, several reports of serious harm and even death have been reported under the circumstances wherein patients cut and apply a reservoir membrane of the Fentanyl patch directly on their skin. Such patients aimed to reduce the dose that was delivered; however, ended up overdosing on the drug.
There are a number of transdermal drug delivery systems that exist in the United States.
Reservoir membrane-modulated system (e.g. “Duragesic” fentanyl–Janssen)
In such products, the substance is contained in a reservoir in the middle of a rate-controlling microporous membrane and an impermeable backing layer. The drug release will be controlled by the former. Once the patch is cut, it actually makes the entire dose available to the user immediately.
Micro-reservoir system (e.g. “Catapres-TTS” clonidine–Boehringer Ingelheim)
The drug is contained in several smaller drug reservoirs within the patch. Cutting the patch could destroy some of these reservoirs. However, most stay intact. Those that remain may no longer be proportionate to the surface area of the patch. Cutting the patch in two would not guarantee that the portion of the drug in both halves is equal.
Adhesive layer systems (e.g.”Lidoderm” lidocaine–Endo)
The drug can be mixed homogeneously with an adhesive that is polymer-based and can be applied directly to an impermeable material. In this case, the amount of drug delivered to the system is diffusion-controlled and also directly proportional to the surface area of the patch. If this patch is cut, it may decrease the amount of drug that can be delivered without being hazardous. It can safely be cut for a smaller dose delivery.
The Matrix system (e.g. “Vivelle-Dot” estradiol–Novartis)
The drug can be evenly distributed throughout the adhesive matrix within the patch just like in adhesive layers. With this type, the amount of drug available can be directly proportional to the surface area of the patch. It is possible to cut the patch but the efficacy of the adhesive will also be reduced.
The majority of Fentanyl patches made available are reservoir membrane-modulated systems.
In such products, the labeling strictly notes that the patches should never be altered or cut. Mylan offers Fentanyl Transdermal Matrix System Patch. The labeling of such also warns against dividing, cutting or damaging the patch pre-application. A formal study to determine cut Fentanyl matrix patches’ clinical effectiveness is yet to be done.
Fentanyl Transdermal patches should NEVER be cut in hopes of titrating doses. Health care providers should instead offer patients new prescription with reduced strength.